Pressure relief means for pneumatic tube systems



A. A. ZIMMER -May 26,1931.

PRESSURE RELIEF MEANS FOR PNEUMATIC TUBE SYSTEMS Filed Dec. 28, 1929 [:jSTATION A Zi Z ae 7 Patented May 26, 1931 UNITED STATES- ARNOLD A.

PATENT ,GIFFICEI i ZIMMER, OF CHICAGO,- ILLI-NOIS, ASSIGNORTO THE LAMSON COMPANY, 01 SYRACUSE, NEXV YORK, A CORPORATION OF 'MASSAiCHUSETTS IPRESSURE RELIEF MEANS FOR PNEUMATIC TUBE SYSTEMS Application filed December 28, 1929. Seria1 No. 417,093.

This invention pertains-to pneumatic despatch systems and more particularly to means for rapidly and automatically restoring normal pressure conditions in the trans- 5 mission tube of such a system after discharge of a carrier therefrom; The utility of the invention is well illustrated in its embodi ment in asingle tube pressure system in which carriers are sent in either direction through the same tube by pressure, and particularly when the sending and receiving stations are at a long distance apart.

Such systems usually comprise a transmission tube extending from one station to the other and provided at itsopposite ends with terminals which are designed for 'despatching and also for delivering carriers. Each terminal is provided with a cover or valve at its entrance opening and this cover or valve, while normally open, is held firmly closed during'tran'sit of a carri-er by suitable means such as a pressure-operated latch. Eachstation is provided with suitable means for supplying air under pressure to'the d-espatch end of the tube; 7 Such supply means may consist of a tank of compressed air provided with a suitable valve controlled outlet, or of a blower driven by any desired term of motive means, for example an individual electric motor. At each station there is provided means for initiating the flow of compressed air through the tube, and the system also comprisesmeans for stopping such flow when the carrier is delivered from the tube, such stopping means usually comprises a timing arrangement or other automaticmeans which cuts off the flow at the proper time without further attention on-the part of the operator. When in such'a system a carrier is introduced 40; into the tube at one station and the cor- 5 carrier.-

Since considerable pressure isnece'ssary to drive thecarrier, and as air is a highly elastic medium, the delivering of the carrier from the tube does not result in an immediate and complete release of pressure throughout the whole tube, especially if the tube is of great length. hen as above suggested the cover at the despatch end is held closed by an airoperated latch, it is found that a' considerable time, for example two orthree minutes, may elapse after discharge of thecarrier from the delivery end of the tube before the pressure within the tube at the despatch end falls low enough to permit release of the latch from its pressure-actuated retainingmeans. This delay is very troublesome when rapid despatch of successive carriers is required, and in accordance with the present invention I have provided means for-cooperation with the otherparts or" such a system whereby this delay in transmission is greatly reduced. In accordance with the present improved practice an unloading or relief valve is provided adjacent to eachstation, said unloading or relief valve being so constructed as automatically, upon discharge of a carrier from the delivery end of the tube to allow air to escape from the despatch end ofthe tube so that the pressure actuated latch retaining means at the despatchend quickly responds to discharge of the carrier and permits the terminal cover toopenfor the reception of another carrier.

' In the accompanying drawings certain desirable embodiments'of the invention are il lustrated by. way of example and in the drawings; V

Fig. '1 is a diagrammatic elevation, with certain parts broken away and certain parts in section, illustrating the present invention as applied to a single tube pneumatic system of the pressure type, and with a carrier just Fig. 8 is a'diagrammatic elevation partly in section and to somewhat larger scale than Fig. 1 illustrating a modifying form of relief valve.

Referring to the drawings, the system illustrated comprises stations A and B connected by a single transmission tube 1 in which carriers are adapted to move in either direction. The tube is providedat its ends with terminals 2 and 3 located at the stations A and B respectively. Since these terminals and all of the parts associated therewith are substantially alike, the, following description will be confined to the terminal 2 and parts directly associated therewith. The terminal 2 is adaptedboth for receipt and despatch of carriers and is provided with an opening, preferably directly in alignment with and below the lower end of the tribal, through which carriers maybe introduced into the tube 1 or from which they may be 1 discharged- Normally this opening is uncovered for the free entrance or discharge of carriers, but upon despatch of the carrier from the terminal 2,,the opening is temporarlly closed and held closed during transit of the'carrler For closing this opening a cover or valve 4 plvoted at 5 is provided. Thls cover may be held closed in air-tight contact withthe end of the terminal casing b means of a latch 6 pivoted at 7 ona suitable support and is preferably provided with a light spring tending to hold it in a release position; Fhis latch also has a tail portion 8 adapted to be moved by a suitable pneumatic, as for example the diaphragm 9. This diaphragm is mounted within a suitable housing forming a part of the terminal structure and having an inner wall provided with a small opening 10 giving communication between the space at the inner side of the diaphragm and the inside of the transmission tube. Preferably the tube 1 is furnished with an extension 11 disposed within the terminal casing and forming aguide for car-.

riers as they pass through the terminal. This extension is provided with perforations 12- for the free passage of air from the interior of the terminal into the tube.

Air is suppliedfor driving the carrier by means of a conduit 13 connected to a lateral arm of the terminal 2, such conduit being connected to a suitable source of air under pressure, for example a tank, or as here shown, to a blower 14. As illustrated this blower is driven by an individual electric motor 15. This motormay be started by means of a button or switch 16 at the station A and may be stopped, if desired, at the will of the operator by actuation of a second switch or button 17 However, under normal conditions of operation, the stopping of the motor is controlled by a suitable timing device 18 which may be of any usual and well-known character familiar to those skilled in the art and comprising clockwork, electrical means,

pneumatic means, or the like for determin ing a fixed and predetermined timeinterval, and for opening the motor circuit at the end of such interval. Since such timing devices are well known it is needless to describe the conduit toward the blower, but-:which.

opens freely in responseto thepressureof air delivered by the blower. Preferably a pipe '21 leads from the valve housing 19 to a safety valve 22 so arranged that when the check valve is closed the pressure in the conduit 13 and the transmission tube excessive.

At a point intermediate the valve housing. 19 and the terminal 2 the conduit 13 is pro-.

vided withan outlet, here shown asa branch pipe 23 open to the atmosphere at the point 24:. At a suitable. point in the length of thispipe provide an unloading or relief valve housing 25. This housing is provided with a suitable valve seat for engagement by a valve 26, thereby. to close the passage through the outlet pipe 23. The valve 26 is prefer-.

ably provided witha stem 27 connected by means of a link 28 to a suitable actuating pneumatic, for example a diaphragm 29 disposed within a housing supported by the valve casing 25. A pipe 30 leads from the space below the diaphragm 29 to the conduit.

13 at a point between the outlet 23 and the terminal 2, while asecond pipe 31 leads from the space above the diaphragm 29 to the conduit 13 at a point below or on the supply side of the check valve 20. A weight 32, secured to a lever arinpivoted at 33 andconnected to the valve stem 28, normally tends to hold the valve 26 against its seat so as to shut the outlet 23. i

It being understood that the station B is provided with a terminal and controlling.

apparatus similar to that'described as pro.-

vided at the station A, the operation is substantially as follows:

Assiuning that the cover 4 at the terminals.

2 and 3 are both open, and that the blowers are both stopped, the operator at station A for example introduces a carrier G into the terminal 2 through the opening at the bottom of the latter and then closes and latches the cover 1. -The operator then presses the button 16 to start themotor 15 into action and thereby drive the blower. Compressed air is now delivered through the conduit 13 (the check valve 20 opening in response to the; air pressure) and passinginto the terminal- 2 forcesthe'diaphragm 9 outwardly with.

such pressure as to prevent manual releaseof I latch 6.. The air also passes through the perforations 12 and drives the carrierG before it through the tube 1 toward theterminal 3.

The starting of the motor also sets the I 1 can not become delivered at the terminal 3 and the motor andblower are stopped, and air is no longer supplied under pressure to the conduit 13, the check valve immediately closes, and as the impeller of the fan stops,the pressure in that portion of the conduit 13 below the check valve immediately falls substantially to atmospheric pressure. On the other hanc the body of compressed air in the long transmission tube 1 does not escape instantaneously from the open terminal 3 so that a substantial pressure is still maintained in that part of the tube 1 which is adjacent to the terminal Q 2 and in the upper part of the conduit 13.

This pressure acting upon the diaphragm 9 prevents release of latch 6 by the operator, but on the other hand it acts through the pipe upon the under side of the diaphragm 29 to raise the latter, it being remembered that the upper side of this diaphragm is now exposed to atmospheric pressure through the. P p 1-.

The lifting of diaphragm 29 opens the unloading or relief valve 26, thus permitting free escape of air through the outlet pipe 23. As this outlet is of substantial size, the pressure in the conduit 13 and in the tube 1 adjacent to the terminal 2 drops very rapidly, whereupon the diaphragm 9 moves inwardly under the action of the latch spring, thusreleasing the latch 6 from the cover and per mitting the latter to drop open. The ter minal is now ready for the despatch of an other carrier either from the terminal 2 or from the terminal 3.

In Fig. 3 I have illustrated a modified construction of relief or unloading valve and in this figure the blower 15, the check valve casing 19 the air supply conduit 13, the outlet pipe 23 and the relief valve proper 26 corresponds substantially to the parts 15} 19, 13, 23 and 26 of Fig. 1. However in this construction the valve 26? is secured to a outlet pipe 23 open to the atmosphere. Thepipe 31 which corresponds to the pipe 31 of Fig. 1, extends from a point below the check valve casing 19 to the space above the dia phragm 29 but in this arrangement there is no pipe corresponding to the pipe 30 of Fig. 1.

lVhen the motor is started, the blower 15 delivers air under pressure into the conduit 13 and as the pressure builds up it is transmitted-through the pipe 31 to the space above the diaphragm 29*, thus overcoming the springs 41 and closing the valve 26*. The

valve remains closed during the transit of the carrier through the tube 1 but as soon as the motor stops the pressure above the diaphragm 29 is relieved and the springs 41 imn'iediately open the valve 26, thus relieving the pressure atthe despatch terminal.

As above described and illustrated the system comorisesindependent motors and blow- L 1 l ers at the statlons A. and B but I contemplate that the air supply for both stations may be provided by a single blow-er, tank, or the like,

and that the air delivered to the terminal at each station may be controlled by means of suitable valves and beiiurnished, ifdesired,

from a common source of supply. I also contemplate that various changes in size, proportion and relative arrangement of parts as well as the substitution of equivalents for the parts here specifically described may be mace without departing from the spirit of the invention,.and when in the annexed claims I refer to av despatch and a delivery terminal, I employ these terms in a purely relative sense, since either terminal may be a despatch or delivery terminal according to circumstances.

l claim:

1. A pneumatic despatch system of the kind having atransmission tube provided with a despatch and a delivery terminal, means for supplying air under pressure to the tube at the despatch end of the latter, means for closing the despatch terminal during transit of a carrier, means for initiating and stopping the'supply of air to' the transmission tube,

and relief means responsive to cessation of the air supply for quickly releasing the pressure within the despatch end of the tube while the despatch terminal remains closed.

2. A pneumatic despatch system having a transmission tube provided with a despatch and a delivery terminal, a conduit for supplying air under pressure to the tube at a point adjacent to the despatch terminal, means for initiatingand stopping the flow of air through said supply conduit, the latter having an outlet at an intermediate point in its length, a relief valve for closing said outlet, and means responsive to cessation of the flow of compressed air "through said con duit for opening the relief valve.

3. A pneumatioclespatch system of vthe kind havinga transmission tube provided with a despatch and a delivery terminal which are closed and open respectively during the transit or" a carrier through the tube, means for creating a carrier impelling air fiow through the tube, and pneumatically actuated means automatically responsive to cessation of the air flow through'the tube andoperative upon the discharge of a carrier from the delivery terminal for opening substantially direct communication between the despatch end of the tube and the outer atmos phere. 7

4s. A pneumatic despatch system of the kind having a transmission tube provided with a despatch and a delivery terminal, means normally closing the despatch terminal during transmission of a carrier, means for delivering air under pressure to the tube for impelling a carrier from the despatch to the delivery terminal, and pneumatically actuated means automaticallyresponsive to cessation of the carrier impelling flow and operative upon the discharge of a carrier from the delivery terminal fer permitting the pressure within the transmission tube adjacent to the despatch terminal to drop quickly substantially to atmospheric pressure.

5. A pneumatic despatch system of the single tube pressure type having a transmission tube carrying an impelling air flow and provided at each'end with a terminal adapted alternatively for despatching and delivering carriers, each such terminalcomprising means for closing it after despatch of a carrier therefrom, and means automatically responsive to cessation of the impelling air flow and operative upon delivery of a carrier from the tube for relieving the air pressure Within the despatch end of the tube.

6. A pneumatic despatch system of the single tube pressure type having a transmission tube provided at each end With a terminal adapted alternatively for despatching and delivering carriers, means for closing one of said terminals during the transit of a carrier through the tube, means for creating a carrier impelling air flow in the tube and for cutting off such flow upon delivery of the carrier from the tube, and means automatically responsive to cessation of the carrier impelling-air flow and operative to open communication between the closed end of the tube and the outer atmosphere When the carrier impelling air flow ceases. I

7. A pneumatic despatch system of the kind having a transmission tube provided with a despatch andra delivery terminal, means normally closing the despatch terminal during transit of a carrier through the tube, means for creating a carrier impelling air flow in the tube and for stopping said flow when the carrier is discharged from the delivery terminal, and means responsiveto the cessation of carrier impelling air flow in the tube for opening communication between the despatch end of the tube and the outer atmosphere. i V

8. A pneumatic despatch system of the kind having a transmission tube provided with a despatch and 'a' delivery terminal,

means normally closing the despatchterminal during transit of a carrier through the tube, means for creating a carrier impelling air flow in the tube and for automatically stopping said flow after a predetermined time interval, and [automatic means responsive to cessation of carrier impelling flow in the tube for opening communication-between the despatch end of the tube and the outer atmosphere.

9. A pneumatic despatch system of the kind having a transmission tube provided with a despatch anda delivery terminal, means for delivering air under pressure to the tube for propelling a carrier from the despatch to the'delivery terminal, means for closing the despatch terminal during trans-- it of a carrier, said closing means remaining closed-so long as the pressure in the tube is substantially above that ofthe atmosphere, and means responsive to cessation of carrier impelling air flow in the tube for permitting air under pressure within the despatch end of the tube to escape.

10. A pneumatic despatch system ofthe' kind having a transmission tube provided with a despatch and a delivery terminal, means for delivering air under pressure to the tube for propelling a carrier from the despatch to the delivery terminal, means for closing the despatch terminal during transit of a carrier, pneumatic means for retaining said closing means in operative position to close the despatch terminal solong as the pressure in the tube is substantially above that of the atmosphere, and-means for releasing the pressure at the despatch end of the tube upon delivery of a carrier from the tube and while the despatch terminal remains closed.

11. A pneumatic despatch system of the kind having a transmission tube provided with a despatch and a delivery terminal, means for delivering air under pressure to the tube for propelling a carrier from the despatch to the delivery terminal, means for closing the despatch terminal during transit of a carrier, a pneumatically actuated latch device for holding the closing means in operative position to close the despatch terminal so long as the pressure in the tube is above that of the outer atmosphere, and means responsive to cessation of carrier impelling air flow for releasing the pressure at the despatch end of the. tube while the despatch terminal remains closed.

12. In combination in a single tube pressure operated pneumatic system, an unloading valve forautomatically releasing the air pressure in the despatch endof the tube upon the delivery of a carrier fromthe tube, and while the despatch terminal remains closed.

13. In combination in a single tube pneumatic system having means for creating a carrier impelling air current in the tube, an unloading valve for releasing the air pressure in the despatch end of the tube, and means responsive to stopping of said current creating means for actuating said unloading valve.

14. A pneumatic despatch system having a transmission tube provided with a despatch and a delivery terminal, means closing the despatch terminal curing transit of a carrier, a conduit for supplying air under pressure to the tube at a point adjacent to the despatch terminal, means for starting and stopping the flow of air through the conduit, the latter having an outlet at a point intermediate its ends, a relief valve which closes said outlet during transmission of a carrier through the tube, and a pneumatic responsive to pressure in the conduit for determining the position of the relief valve.

15. A pneumatic despatch system having a transmission tube provided with a despatch and a delivery terminal, means closing the despatch terminal during transit of a carrier, a conduit for supplying air under pressure to the tube at a point adjacent to the despatch terminal, means for starting and stopping the flow of air through the conduit, the latter having an outlet at a point intermediate its ends, a relief valve which closes said outlet during transmission of a carrierthrough the tube, and motor means responsive to cessation of air flow in the conduit for opening the relief valve.

16. A pneumatic despatch system having a transmission tube provided with a despatch and a delivery terminal, means closing the despatch terminal during transit of a carrier, a conduit for supplying air under pres sure to the tube at a point adjacent to the despatch terminal, means for starting and stopping the flow of air through the conduit, the latter having an outlet at a point intermediate its ends, a relief valve which closes said outlet during transmission of a carrier through the tube, and motor means for actuating the relief valve, said motor means comprising a pneumatic exposed at one side to the air pressure in said conduit.

17. A. pneumatic despatch system having a transmission tube provided with a despatch and a delivery terminal, means closing the despatch terminal during transit of a carrier, a conduit for supplying air under pressure to the tube at a point adjacent to the despatch terminal, means for starting and stopping the flow of air through the conduit, the latter having an outlet at a point intermediate its ends, a relief valve which closes said outlet during transmission of a carrier through the tube, a check valve in the conduit adapted to close the conduit and thereby to prevent reverse flow of air in the conduit, motor means for actuating the relief valve, said motor means including a pneumatic, and a --of'- the check valve.

pipe leading from one side of the pneumatic to a point in the eonduitat the supply side 18. A pneumatic despatch system having a transmission tube provided with a despatch and a delivery terminal, means closing thedespatch terminal during transit of a carrier, a conduit for supplying air under pressure to the tube at a point adj-acentto the despatch terminal, means for starting and stopping the flow of throughthe' conduit, the latter having an outlet at a point intermediate its ends, a reliefvalve which closes said outlet during transmission of a carrier through the tube, a check valve inthe conduit arranged to close when .the'supply of compressed air is cut off thereby to prevent reverse air flow in the conduit, motor means including a pneumatic for actuating jthe relief valve,and pipes leading from opposite sides ofzsaid pneumatic to points in the com pressed air conduit at opposite sides respec tively of the check valve. r i

19. A pneumatic despatch system having a transmission tube provided with a despatch stopping the flow of air through the conduit, the latter having an outlet at a point intermediate'its ends, a relief valve which closes the relief valve;

20. .A pneumatic despatch system having a transmission tube provided with a despatch and a -,del='ivery terminal, means: closing the -c'lesjpateh terminal during transit of ajcarrier, a conduit for supplying air under pres sure to, the tube at a point adjacent to the despatch terminal, means for starting and stopping the flow of air through the conduit,

the latter having an outlet at a point intermediate its ends, a relief valve which closes said outlet during transmission of a carrier through the tube, means arranged automatically to prevent reverse air flow in the conduit when the air supply is cut oil", and means moving in response to the differential pressures at opposite sides of said reverse preventing means, after the air supply is cut ofl, for opening the relief valve.

21. Unloading means for a pneumatic despatch system having a transmission tube and air supply conduit provided with a check valve, said unloading means comprisinga relief valve controlling an outlet intermediate the ends of the conduit and at the and adelivery terminal,- means closing the despatch term-'mal during transit of a care rier, a conduit for supply'ingairunderpres? sure to the tube at a point adjacent to the despatchterminal, means for; starting and delivery end of the check valve, a pneumatic I the pneumatic to a point in the conduit at the supply side of the check valve.

22. A pneumatic despatch system having a transmission tube provided with a despatch and a delivery terminal, means closing the despatch terminal during transit of a carrier, a blower for supplying compressed air to the tube, motive means for driving the blower, a conduit for delivering air from the blower to the despatch end of the tube, means for starting and stopping the motive means, a check valve for preventing reverse flow of air through the conduit, the latter having an outlet at the delivery side of the check valve, a relief valve closing said outlet during transit of a carrier through the tube, means normally holding said relief valve closed, a pneumatic for opening-the valve,

and pipes leading from opposite sides of the pneumatic to points in the conduit at opposite sides respectively of the check valve.

23. A pneumatic 'despatch system having a transmission tube provided with a despatch and-a delivery terminal, means closing the despatch terminal during transit of a carrier, a blower'for supplyingcompressed air to the tube, motive means for driving the blower, a conduit for delivering air from the blower to the despatch end of the tube, means for starting and stopping the motive means, a check valve for preventing reverse flow of air through the conduit, the latter having an outlet at the delivery side of the check valve, a relief valve closing said outlet during transit of a carrier through the tube, a safety valve connected to the conduit at the delivery side of the check valve, and controlling means for the relief valve comprising a pneumatic and a pipe leading from one side of the pneumatic to a point in the conduit at the supply side of the check valve.

Signed by me at Chicago, 111., this 20th day of Dec., 1929. r ARNOLD A. ZIMJVEER. 

